77 lines
2.0 KiB
C++
77 lines
2.0 KiB
C++
// Copyright Louis Dionne 2013-2017
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// Distributed under the Boost Software License, Version 1.0.
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#include <boost/hana/assert.hpp>
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#include <boost/hana/at_key.hpp>
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#include <boost/hana/contains.hpp>
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#include <boost/hana/map.hpp>
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#include <boost/hana/pair.hpp>
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#include <boost/hana/string.hpp>
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#include <functional>
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#include <string>
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#include <vector>
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namespace hana = boost::hana;
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template <typename ...Events>
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struct event_system {
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using Callback = std::function<void()>;
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hana::map<hana::pair<Events, std::vector<Callback>>...> map_;
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template <typename Event, typename F>
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void on(Event e, F handler) {
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auto is_known_event = hana::contains(map_, e);
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static_assert(is_known_event,
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"trying to add a handler to an unknown event");
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map_[e].push_back(handler);
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}
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template <typename Event>
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void trigger(Event e) const {
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auto is_known_event = hana::contains(map_, e);
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static_assert(is_known_event,
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"trying to trigger an unknown event");
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for (auto& handler : this->map_[e])
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handler();
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}
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};
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template <typename ...Events>
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event_system<Events...> make_event_system(Events ...events) {
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return {};
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}
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int main() {
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auto events = make_event_system(
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BOOST_HANA_STRING("foo"),
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BOOST_HANA_STRING("bar"),
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BOOST_HANA_STRING("baz")
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);
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std::vector<std::string> triggered_events;
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events.on(BOOST_HANA_STRING("foo"), [&] {
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triggered_events.push_back("foo:1");
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});
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events.on(BOOST_HANA_STRING("foo"), [&] {
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triggered_events.push_back("foo:2");
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});
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events.on(BOOST_HANA_STRING("bar"), [&] {
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triggered_events.push_back("bar:1");
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});
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events.on(BOOST_HANA_STRING("baz"), [&] {
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triggered_events.push_back("baz:1");
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});
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events.trigger(BOOST_HANA_STRING("foo"));
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events.trigger(BOOST_HANA_STRING("bar"));
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events.trigger(BOOST_HANA_STRING("baz"));
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BOOST_HANA_RUNTIME_CHECK(triggered_events == std::vector<std::string>{
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"foo:1", "foo:2", "bar:1", "baz:1"
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});
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}
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